From mboxrd@z Thu Jan 1 00:00:00 1970 From: William Thompson Subject: Re: Network problem with bridge and virtualbox Date: Mon, 3 Oct 2011 07:30:44 -0400 Message-ID: <20111003113044.GR19871@electro-mechanical.com> References: <20110929124941.GA16567@electro-mechanical.com> <20110930171839.2893bfa6@nehalam.linuxnetplumber.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: Stephen Hemminger Return-path: Received: from mail.electro-mechanical.com ([216.184.71.30]:57843 "EHLO mail.electro-mechanical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755084Ab1JCLau (ORCPT ); Mon, 3 Oct 2011 07:30:50 -0400 Content-Disposition: inline In-Reply-To: <20110930171839.2893bfa6@nehalam.linuxnetplumber.net> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, Sep 30, 2011 at 05:18:39PM -0700, Stephen Hemminger wrote: > On Thu, 29 Sep 2011 08:49:41 -0400 > William Thompson wrote: > > > Please keep me in the CC as I am not subscribed. > > > > I'm using a 64-bit kernel 3.0.0 and virtualbox 4.1.2. > > > > My problem is that I cannot ping the host from a virtual machine. > > > > My bridge is configured as follows: > > # brctl addbr br0 > > # brctl setfd br0 0 > > # brctl stp br0 off > > # ifconfig br0 10.2.3.1 netmask 255.255.255.0 > > > > In the virtual machine, it is set to use br0 as it's interface (bridge mode) > > and it's IP is 10.2.3.10. > > > > The host gets packets from the vm, but the vm does not receive packets back. > > > > I have this same setup working on a 32-bit kernel 2.6.38.6 on another > > machine with virtualbox 4.0.4. > > > > I had a thought that the bridge on the host wasn't responding due to having > > no ports configured so I added one of my spare ethernet cards to it as > > follows: > > # brctl addif br0 eth1 > > # ifconfig eth1 up > > > > The card was plugged into a switch. After doing this, the vm still could not > > talk to the host. I added a physical machine to the switch that eth1 was > > connected to and configured it to 10.2.3.2. I was able to ping 10.2.3.2 but > > not 10.2.3.1 > > Did you add any interface to the bridge? Initially, no. > I think you were bit by the change in carrier behavior. No carrier on the > bridge interface tracks the union of the devices in the bridge. > Several people have been using bridge in strange way (as a dummy device) > with no physical interfaces and some applications are checking for carrier. That's how I have been using it. Using it as a dummy, ie no interfaces added to the bridge, on 3.0.0 I was unable to communicate with the host from the VM. I added eth1 to it. This has a link to a physical network. I assigned IPs to the host and the VM to be on the same network that eth1 was attached. From the VM I could communicate with devices on the physical network but not the host. The host could also communicate with the other devices.